RxAndroid Error Handling

RetrofitException.java

public class RetrofitException extends RuntimeException {
    public static RetrofitException httpError(String url, Response response, Retrofit retrofit) {
        String message = response.code() + " " + response.message();
        return new RetrofitException(message, url, response, Kind.HTTP, null, retrofit);
    }

    public static RetrofitException networkError(IOException exception) {
        return new RetrofitException(exception.getMessage(), null, null, Kind.NETWORK, exception, null);
    }

    public static RetrofitException unexpectedError(Throwable exception) {
        return new RetrofitException(exception.getMessage(), null, null, Kind.UNEXPECTED, exception, null);
    }

    /** Identifies the event kind which triggered a {@link RetrofitException}. */
    public enum Kind {
        /** An {@link IOException} occurred while communicating to the server. */
        NETWORK,
        /** A non-200 HTTP status code was received from the server. */
        HTTP,
        /**
         * An internal error occurred while attempting to execute a request. It is best practice to
         * re-throw this exception so your application crashes.
         */
        UNEXPECTED
    }

    private final String url;
    private final Response response;
    private final Kind kind;
    private final Retrofit retrofit;

    RetrofitException(String message, String url, Response response, Kind kind, Throwable exception, Retrofit retrofit) {
        super(message, exception);
        this.url = url;
        this.response = response;
        this.kind = kind;
        this.retrofit = retrofit;
    }

    /** The request URL which produced the error. */
    public String getUrl() {
        return url;
    }

    /** Response object containing status code, headers, body, etc. */
    public Response getResponse() {
        return response;
    }

    /** The event kind which triggered this error. */
    public Kind getKind() {
        return kind;
    }

    /** The Retrofit this request was executed on */
    public Retrofit getRetrofit() {
        return retrofit;
    }

    /**
     * HTTP response body converted to specified {@code type}. {@code null} if there is no
     * response.
     *
     * @throws IOException if unable to convert the body to the specified {@code type}.
     */
    public <T> T getErrorBodyAs(Class<T> type) throws IOException {
        if (response == null || response.errorBody() == null) {
            return null;
        }
        Converter<ResponseBody, T> converter = retrofit.responseBodyConverter(type, new Annotation[0]);
        return converter.convert(response.errorBody());
    }
}

RxErrorHandlingCallAdapterFactory.java

public class RxErrorHandlingCallAdapterFactory extends CallAdapter.Factory {
    private final RxJavaCallAdapterFactory original;

    private RxErrorHandlingCallAdapterFactory() {
        original = RxJavaCallAdapterFactory.create();
    }

    public static CallAdapter.Factory create() {
        return new RxErrorHandlingCallAdapterFactory();
    }

    @Override
    public CallAdapter<?> get(Type returnType, Annotation[] annotations, Retrofit retrofit) {
        return new RxCallAdapterWrapper(retrofit, original.get(returnType, annotations, retrofit));
    }

    private static class RxCallAdapterWrapper implements CallAdapter<Observable<?>> {
        private final Retrofit retrofit;
        private final CallAdapter<?> wrapped;

        public RxCallAdapterWrapper(Retrofit retrofit, CallAdapter<?> wrapped) {
            this.retrofit = retrofit;
            this.wrapped = wrapped;
        }

        @Override
        public Type responseType() {
            return wrapped.responseType();
        }

        @SuppressWarnings("unchecked")
        @Override
        public <R> Observable<?> adapt(Call<R> call) {
            return ((Observable) wrapped.adapt(call)).onErrorResumeNext(new Func1<Throwable, Observable>() {
                @Override
                public Observable call(Throwable throwable) {
                    return Observable.error(asRetrofitException(throwable));
                }
            });
        }

        private RetrofitException asRetrofitException(Throwable throwable) {
            // We had non-200 http error
            if (throwable instanceof HttpException) {
                HttpException httpException = (HttpException) throwable;
                Response response = httpException.response();
                return RetrofitException.httpError(response.raw().request().url().toString(), response, retrofit);
            }
            // A network error happened
            if (throwable instanceof IOException) {
                return RetrofitException.networkError((IOException) throwable);
            }

            // We don't know what happened. We need to simply convert to an unknown error

            return RetrofitException.unexpectedError(throwable);
        }
    }
}

Usages

subscription = RestApiBuilder
                .getBooksProvider()
                .getBooks()
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .map(new Func1<Books, String>() {
                    @Override
                    public String call(Books books) {
                        return null;
                    }
                })
                .subscribe(new Subscriber<String>() {
                    @Override
                    public void onCompleted() {

                    }

                    @Override
                    public void onError(Throwable e) {
                        RetrofitException error = (RetrofitException) e;
                    }

                    @Override
                    public void onNext(String s) {

                    }
                });

Hi, thank you for this gist!
I use this gist in my project, when the web request returns connect refused by the server, a crash happened, have you ever met it?
Below is the crash log:
java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 1 path at line 56,at line 21,at 37 at 34....